While both fantastic cards I think their extreme nature makes them less well suited for this deck
The thing is, Dinosaur Headdress turns the attached creature into a copy of the exiled card, meaning you dont get any EtB value, which is usually what you want from a reanimator spell
Moria Marauder, although a Goblin, has Orc (and Goblin) tribal support since whenever an Orc (or Goblin) deals combat damage to a player, we can exile the top card of our library and play that card this turn
(2014-11-24) Whether the target creature is still a legal target is not checked after Channel Harm resolves
Volcanic Island was accidentally omitted from Alpha
While we have no confirmation about why Wizards used OM1 for Marvels Spider-Man , the most likely explanation is some licensing conflict with Marvel SNAP having some form of digital-exclusive rights